1. Field of the Invention
This invention relates to a label transfer apparatus and method for use in transferring labels from a label magazine for in-mold labeling prior to blow molding.
2. Background Art
In-mold labeling has previously been performed with rotary wheel type blow molding machines as disclosed by U.S. Pat. Nos.: 4,479,770 Slat et al.; 4,639,207 Slat et al; 4,680,000 Nowicki et al.; 4,834,641 Keyser; 4,909,723 Slat et al.; 4,973,241 Keyser; 5,044,922 Plenzler et al.; 5,104,306 Gordon et al.; and 5,266,149 Collette et al.
Such in-mold labeling is performed by inserting a label within an open mold as the open mold is moved with other molds on a rotary wheel prior to the mold closing about an extruded plastic tube or about a hot plastic preform, whereupon blow molding of the extruded plastic tube or the preform bonds the label within the mold to the plastic and provides a smooth transition between the label and the adjacent blow molded surface. In addition to strengthening the blow molded container that results from this process, the more conventional post blow molding label application operation is eliminated.
In certain rotary blow molding machines, the production is very high, e.g., thousands of containers per hour and some as high as more than fifty thousand containers per hour with injection stretch blow molding machines that blow mold preforms as opposed to the extruded parison type of blow molding. Such high production rates make it difficult to place a label within the mold prior to the blow molding since there is little time to do so during the fraction of a second available to deposit the label within the mold.
Also, rapid in-mold labeling is made more difficult because label magazines in which the labels are stored normally are not capable of delivering the labels at a greater rate than about 60 to 70 labels per minute. Label stacks in which the labels are stored prior to being removed by vacuum pickup dispensing heads do not allow the labels to move away from the stack at a greater rate because air cannot normally move behind the labels fast enough to permit removal of more than 60 to 70 or so labels per minute.
Other prior art label systems noted during an investigation conducted in connection with the invention include U.S. Pat. Nos. 3,575,409 Calvert and 4,293,365 Geyser et al.
An object of the present invention is to provide improved apparatus for transferring labels from a label magazine for in-mold labeling prior to blow molding.
In carrying out the above object, label transfer apparatus constructed in accordance with the invention includes a rotary table that is rotatable about a central axis. A first rotary motor rotates the rotary table about the central axis. A transfer head is rotatable on the rotary table about a rotary axis that is fixed with respect to the table and spaced from the central axis such that table rotation moves the transfer head adjacent the label magazine which stores a stack of labels with an exposed end from which the labels are subsequently dispensed. The transfer head includes a pair of vacuum openings through which a vacuum is supplied. An actuator of the apparatus includes a second rotary motor, a rotary actuator member rotatively driven by the second rotary motor about the central axis independently of the rotary table, and a rotary connector extending between the rotary actuator member and the transfer head to rotate the transfer head with a rolling motion to engage one of the vacuum openings with the label at the exposed end of the label magazine and to initially pull an extremity of the label away from the label stack and thereby permit air to move behind the label, to subsequently pull an intermediate portion of the label away from the label stack and thereby permit more air to move behind the label, and to then engage the other vacuum opening with opposite extremity of the label to finally pull an opposite extremity of the label away from the label stack in a manner that permits high speed labeling.
To provide the high speed labeling, the label transfer apparatus preferably includes a plurality of the label transfer heads supported on the rotary table for rotary motion on the table adjacent the label magazine and for rotary movement with respect to the table under the impetus of the actuator. The actuator of the label transfer apparatus includes a rotary actuator member that rotates about a central rotary axis of the rotary table and also includes an endless belt that extends from the rotary actuator member to the label transfer heads to provide the rotation thereof with respect to the rotary table. At least one tension wheel is mounted on the rotary table with the belt extending thereover to provide tensioning of the belt, and preferably there are a pair of the tension wheels mounted for rotation on the rotary table adjacent the rotary actuator member. Each label transfer head on the rotary table preferably includes a second pair of vacuum openings one of which engages the label adjacent its first extremity to cooperate with said one vacuum opening of the first mentioned pair of vacuum openings to initially pull the label away from the label stack and the other of which engages the label adjacent its opposite extremity to cooperate with the other vacuum opening of the first pair of vacuum openings to finally complete the pulling of the label away from the label stack.
Another object of the present invention is to provide an improved method for transferring labels from a label magazine for in-mold labeling prior to blow molding.
In carrying out the immediately preceding object, the label transferring method is performed by rotating a rotary table by a first rotary motor about a central axis adjacent the label magazine which stores a stack of labels with an exposed end from which the labels are subsequently dispensed. A transfer head is rotatably supported on the rotary table about a rotary axis fixed with respect to the rotary table and spaced from the central axis. A rotary actuator member is rotated about the central axis by a second rotary motor independently of the rotary table and rotates the transfer head by a rotary connector that extends between the rotary actuator member and the transfer head. A vacuum is drawn through a pair of vacuum openings of the transfer head. The rotary table and the transfer head are rotated by the first and second rotary motors in opposite directions to engage one of the vacuum openings with the label at the exposed end of the label magazine to initially pull an extremity of that label away from the label magazine and thereby permit air to move behind the label, to subsequently pull an intermediate portion of the label away from the label stack and thereby permit more air to move behind the label, and to then engage the other vacuum opening with opposite extremity of the label to finally pull an opposite extremity of the label away from the label magazine in a manner that permits high speed labeling.
The method is preferably performed with a plurality of the label heads supported and rotated on the rotary table about associated fixed axes with respect to the table for movement therewith adjacent the label magazine and for rotary movement with respect to the table to provide the rolling motion that pulls each label from the label magazine. Each label transfer head is rotated with respect to the table by the rotary actuator member that rotates about the central axis of the rotary table and by the rotary connector that may be embodied by an endless belt that extends from the rotary actuator member to the label transfer heads. The label transfer method also involves tensioning of the endless belt by a tension wheel rotatably mounted on the rotary table and with the tensioning of the endless belt preferably provided by a pair of tension wheels rotatably mounted on the rotary table.
In the preferred practice of the label transfer method, a first vacuum opening of a second pair of vacuum openings of the transfer head initially also engages the label adjacent its first extremity to cooperate with said one vacuum opening of the first mentioned pair of vacuum openings to initially pull the label away from the label stack and another vacuum opening of the second pair subsequently also engages the label adjacent its opposite extremity to cooperate with the other vacuum opening of the first pair of vacuum openings to complete the pulling of the label away from the label stack.